1. Field of the Invention
The present invention relates to a pyridine derivative and its ruthenium or osmium complex.
2. Discussion of the Background
A dye sensitizing type solar battery which employs a compound having photoelectric exchanging function is described in U.S. Pat. No. 5,463,057. Bipyridine and a ruthenium complex of tetrabipyridine are disclosed as examples for compounds having photoelectric exchanging function.
It is an object of the present invention to provide a novel pyridine derivative and its complex.
This and other objects have been achieved according to the present invention, the first embodiment of which includes a pyridine compound represented by the following formula (I) 
wherein each of R1, R2, R3, R4 is independently xe2x80x94ORxe2x80x2, xe2x80x94COORxe2x80x2, xe2x80x94CONRxe2x80x2, xe2x80x94CHO, xe2x80x94CH2ORxe2x80x2, xe2x80x94CN, an alkyl group whose carbon number ranges from 1 to 20 inclusive, or xe2x80x94COONRxe2x80x24, wherein Rxe2x80x2 is a hydrogen, or an alkyl group whose carbon number ranges from 1 to 4 inclusive.
Another embodiment of the present invention includes a complex of a pyridine compound represented by the following formula (II) 
wherein each of X1, X2, X3, X4 is independently xe2x80x94OR, xe2x80x94COORxe2x80x2, xe2x80x94CONRxe2x80x2, xe2x80x94CHO, xe2x80x94CH2ORxe2x80x2, xe2x80x94CN, an alkyl group whose carbon number ranges from 1 to 20-inclusive, or xe2x80x94COONRxe2x80x24, wherein Rxe2x80x2 is a hydrogen, or an alkyl group whose carbon number ranges from 1 to 4 inclusive;
wherein Z is Cl, Br, CN, NCS, or NCO; and
wherein M is Ru or Os.